Southwestern Florida residents are being alerted to a massive red tide that is blooming and continuing to grow near the coastline.

Researchers are saying that it stretches 60 miles wide and 90 miles long in the Gulf of Mexico, and is the largest since 2005.

NOAA/AP Photo

This satellite image provided by NOAA shows the algae bloom on Lake Erie in 2011.

A red tide is a natural occurrence, and this particular type happens when a microscopic algae multiplies. This algae is called Karenia brevis (K. brevis for short) and produces toxins that can attack the central nervous system of fish and birds.

The red tide is still about 20 miles away from the coast, but if it reaches within 1 mile, that's when it can affect humans. This could be a possibility by the end of the month if weather systems do not interfere. The force of the waves at the shoreline can actually break up the K. brevis molecules and release these toxins into the air. These toxins are not deadly, but can be irritating to people with asthma and allergies, causing upper respiratory problems and a skin rash.

TopPhoto/AP Photo

An algae called noctiluca scintillans mass propagated and caused red tide in Shenzhen, Guangdong, China on April 10, 2012.

Red tides are part of the natural system in the Gulf and have been observed in Florida since the 1700s. Trying to alter or stop the bloom is difficult considering it can affect the well-being of other marine life and animals.